We plan to continue our studies on the axonal cytoskeleton in invertebrate axons. Neurofilaments are being purified from Myxicola and squid giant axons. The structure and composition of these organelles is under investigation. Our studies have shown that the structure of Myxicola and squid neurofilaments are indistinguishable; however, the protein compositions are not identical. We are carrying out immunochemical and physical chemical studies in order to compare Myxicola and squid neurofilaments with vertebrate neurofilaments. BIBLIOGRAPHIC REFERENCES: Lasek, R.J. (1975) Axonal transport and the use of intracellular markers in neuroanatomical investigation. Fed. Proc. 34: 1603-1611. Hoffman, P.N. and R.J. Lasek (1975) The slow component of axonal transport: Identification of strutural polypeptides of the axon and their generality among mammalian neurons. J. Cell Biol. 66: 351-366.